Troubleshooting Git Push Authentication Failures

Git is a powerful version control system, and git push is a fundamental command used to upload local repository content to a remote repository, such as those hosted on GitHub, GitLab, or Bitbucket. However, you may occasionally encounter "Authentication Failed" errors when attempting to push changes. This tutorial explains common causes and solutions to resolve these issues.

Understanding the Error

The "Authentication Failed" error indicates that Git is unable to verify your identity with the remote repository. This can stem from several reasons, including incorrect credentials, changes to your remote account, or outdated cached credentials.

Common Causes and Solutions

Here’s a breakdown of the most frequent causes and how to address them:

1. Two-Factor Authentication (2FA)

If you’ve enabled 2FA on your remote repository account (highly recommended for security!), you can’t use your regular password directly with git push over HTTPS. Instead, you need to create a Personal Access Token (PAT).

How to fix:
1. Go to your account settings on the remote repository platform (e.g., GitHub).
2. Navigate to the "Developer settings" or similar section.
3. Create a new Personal Access Token, granting it the necessary permissions (usually repo).
4. Use the PAT as your password when prompted during git push. Your username remains the same.

2. Incorrect or Outdated Credentials

Your Git client might be caching old or incorrect credentials. This is a common issue, especially if you’ve recently changed your password or email address on the remote repository.

How to fix: Clear the cached credentials. The method varies depending on your operating system:
- Windows:
  1. Search for "Credential Manager" in the Windows Start Menu.
  2. Open the "Windows Credentials" tab.
  3. Look for entries starting with "git:" or "ada:". These are likely your Git credentials.
  4. Edit or remove these entries. Git will prompt you for your username and password the next time you push.
- macOS:
  The Keychain Access application stores credentials. Search for entries related to your remote repository (e.g., github.com) and remove them.
- Linux/macOS (using git credential helper):
  You can explicitly tell Git to forget cached credentials and prompt for them again. Try these commands:
```
git config --global --unset credential.helper
git config credential.helper store
```
  This will prompt you for your username and password on the next push.

3. Password Changes on the Remote Repository

If you’ve recently changed your password on the remote repository, your Git client will still be using the old password if it’s cached. Clearing the cached credentials (as described above) is the solution.

4. Using SSH instead of HTTPS

If you frequently encounter authentication problems with HTTPS, consider switching to SSH. SSH provides a more secure and often smoother authentication experience.

How to switch:
1. Check your remote URL: git remote -v
2. If the URL starts with https://, change it to [email protected]:USERNAME/REPONAME.git (replace USERNAME and REPONAME with your actual values).
```
git remote set-url origin [email protected]:USERNAME/REPONAME.git
```

5. Expired Credentials

Some credential managers have a timeout period. If it’s been a while since you last authenticated, your credentials might have expired. Clearing and re-entering your credentials will resolve this.

Best Practices

Enable Two-Factor Authentication: For enhanced security, always enable 2FA on your remote repository account.
Use SSH: Whenever possible, use SSH for authentication, as it’s generally more reliable and secure than HTTPS.
Regularly Update Credentials: If you change your password, be sure to update your credentials in Git as well.
Consider a Credential Manager: Utilize your operating system’s credential manager to securely store and manage your Git credentials.